Construction of a reinforced earth bund

Question

Construction of a reinforced earth bund

MrRatty (Geotechnical)

(OP)

17 Sep 14 09:24

I've designed a 3.50m high reinforced earth accoustic bund, it's got 45 degree slopes and a 1m wide strip along the top. The contractors on site are wondering how to place and compact the soil now it's about 2m high. For H&S reasons they are reluctant to ave any plant running along it (one false move and it would be rolling down the side). There are also concerns about personnel being on top of it. This will obviously become more onerous the high (and narrower) it becomes.

Has anyone got any practical experience of constructing these things? I know they are commonly built, I've seen many of them that have been finished. The contractor has never built one before and needs some advice.

Thanks

cvg (Civil/Environmental) · Answer 1 · 2014-09-17 11:42:56

well, constructability is one reason that we normally make berms a minimum of 8 feet wide at the top. this allows larger and more efficient construction as well as safety. the extra cost of material may offset the difficult construction of a narrow berm. the contractor will have to use much smaller equipment, hand work, and will take significantly longer to build. the contractor bid the job, hew knew how narrow it was, sound like he is prepping you for a change order.

oldestguy (Geotechnical) · Answer 2 · 2014-09-17 17:38:36

45 degree side slopes sound almost impractical for earth, unless exhibiting high cohesion.

MrRatty (Geotechnical) · Answer 3 · 2014-09-18 05:09:35

I was restricted by the base width available and the height requirements of the bund. It's reinforced so 45 degrees no problem. Just wondering on the safest way to construct the upper layers...

coloeng (Civil/Environmental) · Answer 4 · 2014-09-18 09:55:07

I would be cautious about giving the contractor advice on how to construct this. As cvg mentioned, the contractor bid the project knowing what he was to build and should have had an idea how he was going to construct it. If you tell the contractor how to build it and it doesn't work out the way you hoped, the contractor may be able to come back on you for directing him to do something that didn't work. Make the contractor figure it out, he is the contractor after all. He probably already knows how it needs to be done, but has figured out that it will be more expensive than he thought when he bid the project.

oldestguy (Geotechnical) · Answer 5 · 2014-09-18 11:08:30

Just curious. How do you retain the layers at the edges? If wrapped around geo fabric, is it UV resistant? Erosion resistant? Vegetation? Gunite coating?

MrRatty (Geotechnical) · Answer 6 · 2014-09-18 11:17:00

Topsoil over the wrap then erosion matt on top.

charnott (Civil/Environmental) · Answer 7 · 2014-09-22 05:45:50

smaller plant = smaller weights = smaller layer thickness = more time + cost

thinner layer thicknesses may make the use of handheld compaction plant (whacker plate type) feasible dependant upon the fill material. as others have pointed out, its a pretty basic observation to have made when bidding the work, presuming hes not working to client or designer provided methodology he needs to be coming to you with solutions to his problems

MrRatty (Geotechnical) · Answer 8 · 2014-09-22 05:52:01

The contractor understands his position but has just asked for any advice that may help him build the thing more safely and easily. I was wondering if anyone had experience of building these things and could give any practical advice.

charnott (Civil/Environmental) · Answer 9 · 2014-09-22 06:09:53

understood, people caveats on this forum are always longer than their technical advice not without good reason though given some of the perceived levels of understanding based on some OP's!

cant see anyway round handheld plant for compaction. a hydraulic plate on the end of a long reach might be an option but how accessible that plant would be to obtain I cant say.

make sure you get a good risk assessment if people are required to work atop the slope, operators safety and also those down slope from operators work area would be of concern

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Construction of a reinforced earth bund